Johnson 90 only runs when keep pressing primer bulb

[ib18]

Johnson 90 only runs when keep pressing primer bulb

 

[jakedaawg]

Fuel pump

 

[Boatman_Rollins]

Gonna be your diaphragm in your fuel pump. I'd take a fuel sample first IMO

 

[ib18]

Thanks for the quick reply. Fuel pump is what I was thinking about when I was at the boat dock when motor could not continue to run.
Well, I launched it 2 weekends in a row. Johnson 90 was performing flawlessly. Idling well, runs well, and I use seafoam addition in my external gas tank so hard to imagine it is the carb issue. I researched more and found out yes fuel pump could be bad, but more likely than not it may be the compression issue which again I doubt that is the reason why motor bogged down. I premix my oil with gas 1:50 so no ruptured VRO for leaking oil danger there either.
(1) I will still start off by checking the compression of all 4 cylinders. (2) check the fuel passage from tank to carb in the engine and see what happens. feel free to guess what could be the problem! I will report back after I have time to take a look of my old but faithful outboard - LOL
​

 

[nomorevro]

You can find my post from a week ago same thing on 50hp, My VRO had already been bypassed, so I went with standard fuel pump, $ 42 running like a top again. I don't mind pre mixing my fuel, cause I have to carry to the dock anyways.

 

[JDusza]

Fuel line sucking air somewhere. Start at tank and go through all hose and connections.
J

 

[ib18]

Fuel line sucking air somewhere. Start at tank and go through all hose and connections.
J

you are totally correct, my connection to the external tank was loose. I switched the connection to another external gas tank but didn't screw it all the way in so sucking air at the tank end of the fuel line. I was too anxious to boating so neglected the basic work. It was working on land on my driveway, but it bogged down under load when I got to the boat ramp and left the dock. Lessons learned. Whats worse was I ordered a fuel pump rebuild kit thinking I didn't want to wait for the parts to come if that is the reason why motor bogged down. Now, that part is in storage. The good news is my Johnson 90 is kicking and running like a champ. It clocked in at 30 miles an hour easy with the 2 of us on the boat and a big trolling motor in the front. Didn't push for more but could be going even faster if I want to - lol

 

[ib18]

Motor bogged down again, so rebuilt the fuel pump but broke 1 of the legs, so had to buy a new fuel pump. Now, the motor is kicking and running. Also fixed the fuel leaking from carburetors problem. motor is now running at perfect condition after 2 fixes.

 

[daselbee]

Man you need to learn how to start that thing. Your starting procedure is way wrong.

 

[interalian]

Man you need to learn how to start that thing. Your starting procedure is way wrong.

And it shouldn't crank so slow the first couple of revolutions. After attempts, check if any cable ends are getting warm.

BTW, cold starting procedure:

1) Pump bulb until firm (hold motor end upward while pumping)
2) Lift fast idle to highest position
3) Turn key to 'on'
4) Press key in then turn to 'start' while holding key in (Primer is a valve and operates from fuel pressure pulses while motor is cranking. Dabbing the primer before cranking the motor does little or nothing)
5) Release key when the motor fires
6) Press key in if motor stumbles - should need shorter and less frequent presses as it warms
7) Lower idle lever as motor warms

 

[David Young]

Yep, cranking way too slow. Is your battery any good?

 

[ib18]

Man you need to learn how to start that thing. Your starting procedure is way wrong.

I know, just self taught and never paid attention how to do it right

 

[ib18]

And it shouldn't crank so slow the first couple of revolutions. After attempts, check if any cable ends are getting warm.

BTW, cold starting procedure:

1) Pump bulb until firm (hold motor end upward while pumping)
2) Lift fast idle to highest position
3) Turn key to 'on'
4) Press key in then turn to 'start' while holding key in (Primer is a valve and operates from fuel pressure pulses while motor is cranking. Dabbing the primer before cranking the motor does little or nothing)
5) Release key when the motor fires
6) Press key in if motor stumbles - should need shorter and less frequent presses as it warms
7) Lower idle lever as motor warms

Wow, thanks this is very helpful and I will try it Friday

 

[ib18]

Yep, cranking way too slow. Is your battery any good?

Yes battery is full charge. I will check all connections again

 

[racerone]

Take starter apart for inspection !!---It can be difficult for folks to understand the operation of the simple electric primer valve !